Leisure battery charging circuit

[Poohbear]

I wonder if one of you electrical techies can throw some light on this one for me please?

I have a Bongo with an Imperial conversion and this question may be specific to the conversion but I'll try you with it anyway.

The main battery and leisure battery are connected together with a smart relay (Ryder TF1170-3 - see link)

http://www.rydertowing.co.uk/towbar_rel ... F1170.aspx

The main feed to this relay from the main battery was made badly (i.e. the crimp connector hadn't been crimped properly) but after I had made this connection properly the system still didn't work so I replaced the relay as I figured that the bad connection may have destroyed the relay over the four years since conversion. It now works but seems to work intermittently and I'm not sure why.

On the two switched outputs from the relay there are two wires. One goes to the leisure battery via a 20A fuse, the other is a much smaller wire which appears to go to a relay behind the drivers seat fitted onto the end of the conversion. I say appears because I can't actually see the connection but the relay behind the seat switches in sync with the ryder relay under the bonnet.

My question is: What does the relay behind the drivers seat actually do? I could really do with a wiring diagram but it seems that there isn't one.

Any help I can get would be much appreciated as we're to Devon soon and would like the battery to be charging as we travel.

[AlliDelta]

Have you checked the output from the alternator? Voltage sensing relays require a certain voltage to switch over. If your alternator is on it's last legs it may not be pushing enough volts to switch the relay over to charge the leisure battery. My reading across the battery terminals with the engine running is greater than 15 volts and the relay is working fine. I have a willinton kit and I'm well pleased with it

[Poohbear]

I would have thought that if your alternator output is over 15V on tick-over you have a problem with the regulator. You should check what happens when the engine speed increases. It should only be 14 - 14.5V maximum as far as I am aware.

Come on guys, surely someone is familiar with the Imperial Conversions enough to answer my question?

[Velocette]

Complete guess: Could it be switching certain loads between batteries/ Blinds, radio, lights etc?

[Poohbear]

Finally got a response from the converter. The smaller wire and the relay behind the drivers seat is apparently to switch off the interior lights whilst driving, which is apparently a legal requirement. Interesting. At least I don't have to worry about that wire now during my investigations into why it isn't charging.